Y is the least reactive as it can be extracted from its oxide by heating alone

Y is the least reactive as it can be extracted from

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Y is the least reactive as it can be extracted from its oxide by heating alone but the other two metals cannot. X is more reactive than Z as it reacts with cold water but Z does not. d) Less reactive metals were discovered first and more reactive metals were discovered later. 32 a) i) Removal of oxygen ii) 1 TiO 2 (s) + 2 Cl 2 (g) + 1 C(s) 1 TiCl 4 (l) + 1 CO 2 (g) iii) No atoms are lost / made during a chemical reaction. b) i) Sodium is more reactive than titanium. ii) Sodium / titanium would react with oxygen / air. c) i) All the atoms are the same. ii) Different types of ions bonded together. 33 a) To prevent them from reacting with the air. b) 2 Na(s) + 2 H 2 O(l) 2 NaOH(aq) + 1 H 2 (g) c) These metals react with water producing an alkaline solution. d) A potassium atom is larger than a sodium atom. There is less attraction between the outermost shell electron and the nucleus in a potassium atom. A potassium atom loses its outermost shell electron more readily than a sodium atom. Unit 12 Reacting masses Practice P12.1 page 72 1 Substance Number of moles of substance present Number of particles present Sulphur atoms 0.900 mol 5.42 x 10 23 atoms Zinc ions 6.50 mol 3.91 x 10 24 ions 2 a) Number of carbon dioxide molecules = number of moles of carbon dioxide molecules x L = 1.50 x 6.02 x 10 23 = 9.03 x 10 23
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45 Suggested Answers b) One carbon dioxide molecule contains one carbon atom and two oxygen atoms. Number of atoms present = 3 x number of carbon dioxide molecules = 3 x 9.03 x 10 23 = 2.71 x 10 24 P12.2 page 74 a) (2 x 14.0) g mol –1 = 28.0 g mol –1 b) [63.5 + 2 x (14.0 + 3 x 16.0)] g mol –1 = 187.5 g mol –1 c) [3 x (14.0 + 4 x 1.0) + 31.0 + 4 x 16.0] = 149.0 g mol –1 d) (2 x 1.0 + 32.1 + 4 x 16.0) g mol –1 = 98.1 g mol –1 P12.3 page 76 1 Molar mass of CH 4 = (12.0 + 4 x 1.0) g mol –1 = 16.0 g mol –1 Mass of CH 4 = number of moles of CH 4 x molar mass of CH 4 = 8.00 mol x 16.0 g mol –1 = 128 g 2 Molar mass of Ag 2 O = (2 x 107.9 + 16.0) g mol –1 = 231.8 g mol –1 Number of moles of Ag 2 O = mass of Ag 2 O molar mass of Ag 2 O = 81.2 g 231.8 g mol –1 = 0.350 mol P12.4 page 78 1 a) Molar mass of glucose = (6 x 12.0 + 12 x 1.0 + 6 x 16.0) g mol –1 = 180.0 g mol –1 Number of moles of glucose = mass of glucose molar mass of glucose = 26.1 g 180.0 g mol –1 = 0.145 mol b) Number of glucose molecules = number of moles of glucose x L = 0.145 mol x 6.02 x 10 23 mol –1 = 8.73 x 10 22
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46 Topic 3 Metals 2 a) Molar mass of Zn(NO 3 ) 2 = [65.4 + 2 x (14.0 + 3 x 16.0)] g mol –1 = 189.4 g mol –1 Number of moles of Zn(NO 3 ) 2 = mass of Zn(NO 3 ) 2 molar mass of Zn(NO 3 ) 2 = 84.7 g 189.4 g mol –1 = 0.447 mol b) Number of formula units of Zn(NO 3 ) 2 = number of moles of Zn(NO 3 ) 2 x L = 0.447 mol x 6.02 x 10 23 mol –1 = 2.69 x 10 23 One formula unit of Zn(NO 3 ) 2 contains 1 zinc ion and 2 nitrate ions. Number of zinc ions = 2.69 x 10 23 Number of nitrate ions = 2 x 2.69 x 10 23 = 5.38 x 10 23 P12.5 page 81 1 Formula mass of (NH 4 ) 2 SO 4 = 2 x (14.0 + 4 x 1.0) + 32.1 + 4 x 16.0 = 132.1 Percentage by mass of N in ammonium sulphate = number of atoms of N in formula x relative atomic mass of N formula mass of (NH 4 ) 2 SO 4 x 100% = 2 x 14.0 132.1 x 100% = 21.2% 2 Formula mass of CuSO 4 •5H 2 O = 63.5 + 32.1 + 4 x 16.0 + 5 x (2 x 1.0 + 16.0) = 249.6 Percentage by mass of oxygen in CuSO 4 •5H 2 O = 9 x 16.0 249.6 x 100% = 57.7%
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47 Suggested Answers 3 Let m be the relative atomic mass of X.
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